As is known, pasteurizers for making ice-cream and similar normally comprise a cylindrical mixing bowl, into which the ingredients for a given amount of ice-cream are poured; a heating unit for heating and maintaining the mixing bowl and contents for a predetermined time at a temperature normally ranging between 60° C. and 100° C.; a mixing member mounted for rotation inside the mixing bowl to blend the ingredients uniformly when preparing the ice-cream mixture; and an electronically controlled drive unit for rotating the mixing member at a predetermined angular speed.
More specifically, in known pasteurizers, the mixing bowl is positioned vertically, with the opening projecting outside the casing of the machine, so that the inside of the bowl is accessible and observable directly from the top; and the pasteurizer is fitted with a movable lid hinged to the casing of the machine and movable manually by the user between a lowered position sealing the opening of the bowl, and a raised position allowing free access to the inside of the bowl.
In known pasteurizers, the movable lid normally comprises a shell made of plastic material, and which, excluding the hinges connecting it to the casing, is molded in one piece to reduce the manufacturing cost of the machine.
Though highly efficient, movable lids of the above type have proved fairly fragile, and, more importantly, relatively awkward to clean in daily use, with all the problems this entails.
In addition, lids of the above type are extremely expensive to repair: in fact, the whole lid must be replaced, even in the event of only minor cracks in the plastic shell.